JP2019197773A - Etching method of oxide semiconductor film - Google Patents

Abstract

To provide an etching method of an oxide semiconductor film capable of improving the processing speed of an oxide semiconductor film.SOLUTION: In an etching method for an oxide semiconductor film according to an embodiment of the present disclosure, a reducing layer is formed on the oxide semiconductor film by using a reducing gas, and the reducing layer is sputtered using a rare gas.SELECTED DRAWING: Figure 1B

Description

  The present disclosure relates to, for example, a method for etching an oxide semiconductor film constituting an electronic device.

  As an etching method for a silicon nitride (SiN) film, for example, Non-Patent Document 1 reports an etching method in which an altered layer is formed on the surface by irradiating hydrogen ions, and then the altered layer is removed by irradiating fluorine radicals. ing.

Sonam D. Sherpa and Alok Ranjan. J. Vac. Sci. Technol. A35 01A102 (2017)

  Incidentally, in the etching of an oxide semiconductor film, an improvement in processing speed is required.

  It is desirable to provide a method for etching an oxide semiconductor film that can improve the processing speed of the oxide semiconductor film.

  According to an oxide semiconductor film etching method of an embodiment of the present disclosure, a reducing layer is formed on an oxide semiconductor film using a reducing gas, and the reducing layer is sputtered using a rare gas.

  In the method for etching an oxide semiconductor film according to an embodiment of the present disclosure, a reducing layer is formed on the oxide semiconductor film using a reducing gas, and the reducing layer is sputtered using a rare gas. Accordingly, a layer (reduction layer) rich in a metal element having a high etching rate is formed on the surface of the oxide semiconductor film.

  According to the oxide semiconductor film etching method of an embodiment of the present disclosure, a reducing layer having a high etching rate is formed on the surface of the oxide semiconductor film using a reducing gas, and the reducing layer is sputtered using a rare gas. Thus, the processing speed of the oxide semiconductor film can be improved.

  Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is a cross-sectional schematic diagram for demonstrating the etching method of the oxide semiconductor film which concerns on 1st Embodiment of this indication. It is a cross-sectional schematic diagram showing the process following FIG. 1A. It is a cross-sectional schematic diagram showing the process of following FIG. 1B. It is a characteristic view showing the change of the film composition before and after general etching. It is a schematic diagram of a TEM image of the ITO film after H ₂ plasma irradiation. It is a figure showing the composition ratio of In and O in A and B shown in FIG. 3A. It is a schematic diagram explaining the change of the film | membrane composition of the oxide semiconductor film by reducing gas irradiation. FIG. 4B is a schematic diagram illustrating a change in film composition of the oxide semiconductor film due to reducing gas irradiation subsequent to FIG. 4A. FIG. 4B is a schematic diagram illustrating a change in film composition of the oxide semiconductor film due to reducing gas irradiation subsequent to FIG. 4B. It is a cross-sectional schematic diagram for demonstrating the etching method of the oxide semiconductor film which concerns on 2nd Embodiment of this indication. It is a cross-sectional schematic diagram showing the process following FIG. 5A. It is a cross-sectional schematic diagram showing the etching process of the oxide semiconductor film which concerns on 3rd Embodiment. It is a cross-sectional schematic diagram showing the process following FIG. 6A. It is a cross-sectional schematic diagram showing the process of following FIG. 6B.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. First Embodiment (Example of etching method in which reducing gas and rare gas are irradiated in this order)
1-1. Oxide semiconductor etching method 1-2. Action / Effect Second Embodiment (Example of etching method in which reducing gas and rare gas are mixed and irradiated)
3. Third embodiment (one specific example of etching process)

<1. First Embodiment>
1A to 1C are schematic cross-sectional views illustrating an etching process of an oxide semiconductor film (oxide semiconductor film 12) according to the first embodiment of the present disclosure. The oxide semiconductor film 12 is used as an electrode constituting devices such as various displays such as a flat panel display and a touch panel, a solar cell, and a light emitting diode (LED). In addition, the oxide semiconductor film 12 is also used for an electromagnetic shield, an antireflection film, and the like. The etching method of the present disclosure is suitably used for patterning the oxide semiconductor film 12 constituting the electrode, for example.

(1-1. Oxide Semiconductor Etching Method)
In the etching method of the oxide semiconductor film 12 of this embodiment, after the reducing layer 12M is formed on the oxide semiconductor film 12 by irradiating the reducing gas G1, sputtering is performed using the rare gas G2, and the oxide The semiconductor film 12 is processed into a desired shape. Hereinafter, a method for etching the oxide semiconductor film 12 will be described with reference to FIGS.

  First, as shown in FIG. 1A, the oxide semiconductor film 12 is formed on the support base 11 by using, for example, a dry method or a wet method. Examples of the dry method include a physical vapor deposition method (PVD method) and a chemical vapor deposition method (CVD method). Film formation methods using the principle of the PVD method include vacuum evaporation using resistance heat or high frequency heating, EB (electron beam) evaporation, various sputtering methods (magnetron sputtering or high frequency sputtering), ion plating. Method, laser ablation method, molecular beam epitaxy method, and laser transfer method. Examples of the film formation method using the principle of the CVD method include a plasma CVD method, a thermal CVD method, an organic metal (MO) CVD method, and a photo CVD method. Examples of wet methods include electroplating, electroless plating, spin coating, ink jet, spray coating, stamping, micro contact printing, flexographic printing, offset printing, gravure printing, and dip. It is done.

As described above, the oxide semiconductor film 12 is used as an electrode constituting various devices, for example. Specific materials include, for example, indium oxide, indium-tin oxide (Indium Tin Oxide; including ITO, Sn-doped In ₂ O ₃ , crystalline ITO, and amorphous ITO), and indium as a dopant to zinc oxide Indium-Zinc Oxide (IZO), indium-gallium oxide (IGO) in which indium is added as a dopant to gallium oxide, indium-gallium-zinc oxide in which indium and gallium are added as dopants to zinc oxide (IGZO, In-GaZnO ₄ ), indium-tin-zinc oxide (ITZO) obtained by adding indium and tin as dopants to zinc oxide, IFO (F-doped In ₂ O ₃ ), tin oxide (SnO ₂ ), ATO _(SnO 2 of Sb-doped), FTO (F de Flop SnO 2 _in), zinc oxide (including doped ZnO another element), aluminum was added aluminum as a dopant to zinc oxide - zinc oxide (AZO), added with gallium as a dopant to zinc gallium oxide - zinc oxide (GZO), titanium oxide (TiO ₂ ), niobium-titanium oxide (TNO) obtained by adding niobium as a dopant to titanium oxide, antimony oxide, spinel oxide, and oxide having a YbFe ₂ O ₄ structure. . In addition, a transparent electrode material having a base layer of gallium oxide, titanium oxide, niobium oxide, nickel oxide, or the like can be given.

Subsequently, as illustrated in FIG. 1B, the reducing layer G is formed on the oxide semiconductor film 12 by irradiation with the reducing gas G <b> 1. The reducing gas G1 desorbs oxygen from the oxide semiconductor, and the metal concentration (In / In ₂ O ₃ ratio) of the oxide semiconductor film 12 before irradiation is 1 atomic% or less (the lower limit of detection of In by XPS). Thus, the metal concentration is increased for reduction. The reducing gas G1 includes a reducing gas containing hydrogen and a reducing gas not containing hydrogen. Examples of the reducing gas containing hydrogen include hydrogen (H ₂ ), ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), hydrogen peroxide (H ₂ O ₂ ), methane (CH ₄ ), ethylene ( C ₂ H ₄ ), butane (C ₄ H ₁₀ ) and diborane (B ₂ H ₆ ). Examples of the reducing gas not containing hydrogen include sulfur dioxide (SO ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), carbon monoxide (CO), silicon tetrachloride (SiCl ₄ ), and trichloride. An example is boron (BCl ₃ ).

For example, when the gas containing carbon (C) such as methane (CH ₄ ) is used as the reducing gas G1, the plasma density is preferably about 1E + 10 cm ⁻³ or less, but is not limited thereto. An etching rate can be expected to increase even with a reducing gas G1 having a plasma density higher than 1E + 10 cm ⁻³ . When using a gas not containing carbon (C), the plasma density is preferably used under relatively high-density plasma conditions of 1E + 12 cm ⁻³ or less. In addition, as the reducing gas G1, the above gases may be used alone or in combination.

Next, the reducing layer 12M is sputtered by irradiation with a rare gas G2. Thereby, the reduction layer 12M is removed, and the oxide semiconductor film 12 is etched. The rare gas G2 is selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). As the rare gas G2, the above gases may be used alone or in combination of two or more. After the etching, for example, plasma post-treatment (for example, ashing treatment) including oxygen (O ₂ ), wet cleaning, heat treatment, or the like is preferably performed.

(1-2. Action and effect)
When an oxide semiconductor film such as ITO or IGZO is etched using hydrogen ions, there is a problem in that the composition of the oxide semiconductor film changes with the passage of time, and the characteristics of a device using the oxide semiconductor film deteriorate.

FIG. 2 shows the result of measuring the ratio of In in the ITO film before and after etching using H ₂ / Ar plasma under measurement conditions In 3d _5/2 using X-ray photoelectron spectroscopy (XPS). It is. It can be seen that the In—In bond is increased in the ITO film after the H ₂ / Ar plasma irradiation as compared with before the H ₂ / Ar plasma irradiation.

FIG. 3A schematically shows a TEM image of the ITO film 1012 formed on the substrate 1011 after being irradiated with H ₂ plasma. When the oxide semiconductor film such as ITO is irradiated with H ₂ plasma, a knob-like altered layer is formed on the surface of the oxide semiconductor film as shown in FIG. 3A. FIG. 3B shows the results of measuring the concentrations of In and O in the altered layer portion (A) and the ITO film portion (B) other than the altered layer shown in FIG. 3A using energy dispersive X-ray analysis (EXD). It is a representation. Compared with the ITO film part (B) other than the deteriorated layer, the deteriorated layer part (A) has a higher In concentration, and it can be seen that the deteriorated layer is formed by the aggregation of In.

  As described above, when the oxide semiconductor film is etched using hydrogen ions, for example, in the ITO film, O atoms are desorbed from ITO due to the penetration of H atoms, and the surface becomes In-rich. In the oxide semiconductor film whose surface is In-rich, for example, the insulating property is lowered. An oxide semiconductor is used as an electrode material of a device as described above. For example, an upper electrode and a lower electrode, which are disposed to face each other with a display layer, are formed of an oxide semiconductor film, and are formed by hydrogen ions as described above. When etching is performed using the above, the composition change of the oxide semiconductor film as described above causes a short circuit between the upper electrode and the lower electrode.

  In contrast, in this embodiment, after the reducing layer 12M is formed on the oxide semiconductor film 12 using the reducing gas G1, the reducing layer 12M is sputtered by irradiation with the rare gas G2.

4A to 4C are schematic diagrams for explaining changes in the film composition of the oxide semiconductor film 12 due to reducing gas irradiation. In this embodiment, as illustrated in FIG. 4A, the oxide semiconductor film 12 is irradiated with, for example, carbon monoxide (CO) plasma as a reducing gas. As a result, in the oxide semiconductor film 12, as shown in FIG. 4B, CO takes oxygen (O) from the oxide semiconductor to become carbon dioxide (CO ₂ ), and on the surface of the oxide semiconductor film 12, A reduction layer 12M is formed. As described above, the reduction layer 12M is a region in which the oxygen concentration becomes 50% or less with respect to the oxygen concentration of the oxide semiconductor film before irradiation with the reducing gas due to desorption of O from the oxide semiconductor. This is a region rich in metal elements. Thereby, the sputtering rate of the oxide semiconductor film 12 by the rare gas G2 can be improved.

  As described above, in the etching method of the oxide semiconductor film 12 of this embodiment, after forming the metal-rich reducing layer 12M on the oxide semiconductor film 12 using the reducing gas G1, the rare gas G2 is formed. Was applied to sputter the reduction layer 12M. Therefore, the processing speed of the oxide semiconductor film 12 can be improved.

In addition, dry etching is performed in an etching apparatus. However, as described above, when an altered layer is formed with hydrogen (H ₂ ) and sputtering is performed with a rare gas, it is used for, for example, an upper top plate in the apparatus during H ₂ treatment. The silicon (Si) that is present is sputtered by H ₂ . The sputtered Si sputtered by H ₂ is deposited on the surface of the metal oxide film, which may affect stable processing.

In contrast, in the present embodiment, sulfur dioxide (SO ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), carbon monoxide (CO), tetrachloride that does not contain hydrogen as a reducing gas. By using silicon (SiCl ₄ ), boron trichloride (BCl ₃ ), or the like, sputtering of Si in the etching apparatus is suppressed, and deposition of sputters on the oxide semiconductor film 12 can be prevented. Therefore, the processing stability of the oxide semiconductor film 12 can be improved.

  Note that in this embodiment, the etching method of the oxide semiconductor film 12 is a two-step process in which the reducing layer 12M is formed by irradiating the reducing gas G1, and then the reducing layer 12M is sputtered by irradiating the rare gas G2. Although the example of the etching method performed by (1) was shown, it is not restricted to this. For example, the reducing gas G1 and the rare gas G2 may be alternately irradiated to repeat the formation of the reducing layer 12M and its sputtering. Thereby, since it becomes easy to control the thickness of the reduction layer 12M, it becomes possible to improve processing accuracy.

  Hereinafter, the second and third embodiments of the present disclosure will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

<2. Second Embodiment>
5A and 5B are schematic cross-sectional views illustrating an etching process of an oxide semiconductor film (oxide semiconductor film 12) according to the second embodiment of the present disclosure. The method for etching the oxide semiconductor film 12 of this embodiment is a method in which the reducing gas G1 and the rare gas G2 are mixed and the reduced layer 12M of the oxide semiconductor film 12 is formed and sputtered in one step. is there. Hereinafter, a method for etching the oxide semiconductor film 12 will be described with reference to FIGS. 5A and 5B.

  First, as illustrated in FIG. 5A, the oxide semiconductor film 12 is formed over the supporting base 11 using the above method. Subsequently, as shown in FIG. 5B, for example, a mixed gas in which the reducing gas G1 and the rare gas G2 are mixed at a volume ratio of, for example, 1:10 to 9:10 (reducing gas G1: rare gas G2). Irradiate. Thereby, formation of the reduction layer 12M on the oxide semiconductor film 12 and removal of the reduction layer 12M by sputtering are performed in one step.

As in the first embodiment, the reducing gas G1 is, for example, hydrogen (H ₂ ), ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), peroxide, as a reducing gas containing hydrogen. Examples include hydrogen (H ₂ O ₂ ), ethylene (C ₂ H ₄ ), butane (C ₄ H ₁₀ ) and diborane (B ₂ H ₆ ). Examples of the reducing gas not containing hydrogen include sulfur dioxide (SO ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), carbon monoxide (CO), silicon tetrachloride (SiCl ₄ ), and trichloride. An example is boron (BCl ₃ ). As for the rare gas G2, helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) can be used as in the first embodiment.

The combination of the reducing gas G1 and the rare gas G2 is not particularly limited, and examples thereof include combinations such as H ₂ / Ar, H ₂ / Xe, CO / Ar, and CO / Xe. When the reducing gas G1 and the rare gas G2 are mixed and used as in the present embodiment, the reducing gas G1 is preferably used under the following conditions. For example, when a gas containing carbon (C) such as methane (CH ₄ ) is used as the reducing gas G1, the plasma density is preferably about 1E + 10 cm ⁻³ or less. An increase in the etching rate can be expected even with a reducing gas G1 having a plasma density higher than 1E + 10 cm ⁻³ . When using a gas not containing carbon (C), the plasma density is preferably used under relatively high-density plasma conditions of 1E + 12 cm ⁻³ or less. In addition, as the reducing gas G1, the above gases may be used alone or in combination. Further, the mixed gas used in the etching step of the oxide semiconductor film 12 may be used in combination of two or more kinds of rare gases as the reducing gas G1 and the rare gas G2.

  As described above, in the etching method of the oxide semiconductor film 12 of this embodiment, the reducing gas G1 and the rare gas G2 are mixed and irradiated to the oxide semiconductor film 12, so that the reducing layer 12M is formed. And it becomes possible to perform the sputtering in one process. Therefore, in addition to the effect in the first embodiment, there is an effect that the etching process can be simplified.

<3. Third Embodiment>
6A to 6C are schematic cross-sectional views illustrating an etching process of an oxide semiconductor film (oxide semiconductor film 12) according to the third embodiment of the present disclosure. As described above, the method of etching the oxide semiconductor film 12 of the present disclosure is used in, for example, various devices, electromagnetic shields, antireflection films, and the like. For example, in the display-related, a TN (Twist Nematic) type and For processing of STN (Super Twist Nematic) type liquid crystal display, OLED (Organic Light Emitting Diode), PDP (Plasma Display Panel), FED (Field Emission Display) and electrodes constituting electronic paper, thin film transistor (TFT) and color filter Preferably used. Hereinafter, an example of a specific etching method of the oxide semiconductor film 12 will be described with reference to FIGS.

  First, as illustrated in FIG. 6A, a resist film 21 patterned in a predetermined shape is formed on the oxide semiconductor film 12 formed on the support substrate 11. Subsequently, as shown in FIG. 6B, the reducing gas G1 is irradiated. As a result, the reducing gas G1 enters the oxide semiconductor film 12 exposed from the opening 21H formed in the resist film 21 to form the reducing layer 12M. Next, as shown in FIG. 6C, the reducing layer 12M is sputtered by irradiation with the rare gas G2. Thereby, the reduction layer 12M is etched, and an opening 12H is formed in the oxide semiconductor film 12.

  Note that, as described above, the reduction layer 12M is a region rich in metal atoms whose oxygen concentration is 50% or less than other regions due to desorption of oxygen atoms (O). The reduction layer 12M is also present on the side surface of the pattern formed by etching and on the bottom surface of the opening formed by etching when the etching is stopped halfway.

  As described above, after the resist film 21 patterned in a desired shape is formed on the oxide semiconductor film 12, the reducing layer 12M is formed on the oxide semiconductor film 12 using the reducing gas G1 and the rare gas G2. And the reduction layer 12M was sputtered. Thereby, the processing speed of the oxide semiconductor film 12 can be improved.

In the first to third embodiments, the oxide semiconductor film is described as the film to be etched. However, the etching method of the present disclosure can also be applied to the metal oxide film. Examples of the metal oxide include magnetite (Fe ₃ O ₄ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), and hafnia (Hf ₂ O). ₃ ) and magnesium oxide (MgO). By using the etching method of the present disclosure for processing the metal oxide film, the processing film thickness of the metal oxide film can be controlled, and the metal oxide film can be finely processed.

  The first to third embodiments have been described above, but the present disclosure is not limited to these embodiments and the like, and various modifications can be made.

Note that the oxide semiconductor film etching method of the present disclosure may have the following configuration.
(1)
A reducing layer is formed on the oxide semiconductor film using a reducing gas,
A method for etching an oxide semiconductor film, wherein the reducing layer is sputtered using a rare gas.
(2)
The method for etching an oxide semiconductor film according to (1), wherein the oxide semiconductor film is irradiated with the reducing gas and then the rare gas is irradiated onto the oxide semiconductor film.
(3)
The method for etching an oxide semiconductor film according to (1) or (2), wherein the reducing gas and the rare gas are mixed and irradiated to the oxide semiconductor film.
(4)
The method for etching an oxide semiconductor film according to (1) or (2), wherein the reducing gas and the rare gas are repeatedly irradiated in this order on the oxide semiconductor film.
(5)
The oxide layer according to any one of (1) to (4), wherein the reduction layer is formed by desorption of oxygen atoms from the oxide semiconductor film by irradiation with the reducing gas. Etching method.
(6)
The reducing gas includes hydrogen (H ₂ ), ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), hydrogen peroxide (H ₂ O ₂ ), ethylene (C ₂ H ₄ ), butane (C ₄ H _10). ), Diborane (B ₂ H ₆ ), sulfur dioxide (SO ₂ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ), carbon monoxide (CO), silicon tetrachloride (SiCl ₄ ) and boron trichloride ( The method for etching an oxide semiconductor film according to any one of (1) to (5), wherein at least one of BCl ₃ ) is used.
(7)
The method for etching an oxide semiconductor film according to any one of (1) to (6), wherein the reducing gas has a plasma density of 1E + 10 cm ⁻³ or less.
(8)
The rare gas uses at least one of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe), and any one of (1) to (7) A method for etching an oxide semiconductor film according to claim 1.
(9)
The oxide semiconductor film includes indium oxide, indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-gallium-zinc oxide (IGZO, In-GaZnO). ₄ ), indium-tin-zinc oxide (ITZO), IFO (F-doped In ₂ O ₃ ), tin oxide (SnO ₂ ), ATO (Sb-doped SnO ₂ ), FTO (F-doped SnO ₂ ), Zinc oxide (ZnO), aluminum-zinc oxide (AZO), gallium-zinc oxide (GZO), titanium oxide (TiO ₂ ), niobium-titanium oxide (TNO), antimony oxide, spinel oxide, YbFe ₂ oxide having a O ₄ structure, gallium oxide, titanium oxide, any of niobium oxide and nickel oxide No method of etching the oxide semiconductor film according to any one of (1) to (8).

DESCRIPTION OF SYMBOLS 11 ... Support base material, 12 ... Oxide semiconductor film, 12M ... Reduction layer, 21 ... Resist film, G1 ... Reducing gas, G2 ... Noble gas.

Claims (9)

A reducing layer is formed on the oxide semiconductor film using a reducing gas,
A method for etching an oxide semiconductor film, wherein the reducing layer is sputtered using a rare gas.   The method for etching an oxide semiconductor film according to claim 1, wherein the oxide semiconductor film is irradiated with the noble gas after the reducing gas is irradiated onto the oxide semiconductor film.   The method for etching an oxide semiconductor film according to claim 1, wherein the reducing gas and the rare gas are mixed and irradiated to the oxide semiconductor film.   The method for etching an oxide semiconductor film according to claim 1, wherein the reducing gas and the rare gas are repeatedly irradiated to the oxide semiconductor film in this order.   The oxide semiconductor film etching method according to claim 1, wherein the reducing layer is formed by desorption of oxygen atoms from the oxide semiconductor film by irradiation with the reducing gas. The reducing gas includes hydrogen (H ₂ ), ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), hydrogen peroxide (H ₂ O ₂ ), ethylene (C ₂ H ₄ ), butane (C ₄ H _10). ), Diborane (B ₂ H ₆ ), sulfur dioxide (SO ₂ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ), carbon monoxide (CO), silicon tetrachloride (SiCl ₄ ) and boron trichloride ( The method for etching an oxide semiconductor film according to claim 1, wherein at least one of BCl ₃ ) is used. The method for etching an oxide semiconductor film according to claim 1, wherein a plasma density of the reducing gas is 1E + 10 cm ⁻³ or less.   2. The etching of an oxide semiconductor film according to claim 1, wherein the rare gas uses at least one of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Method. The oxide semiconductor film includes indium oxide, indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-gallium-zinc oxide (IGZO, In-GaZnO). ₄ ), indium-tin-zinc oxide (ITZO), IFO (F-doped In ₂ O ₃ ), tin oxide (SnO ₂ ), ATO (Sb-doped SnO ₂ ), FTO (F-doped SnO ₂ ), Zinc oxide (ZnO), aluminum-zinc oxide (AZO), gallium-zinc oxide (GZO), titanium oxide (TiO ₂ ), niobium-titanium oxide (TNO), antimony oxide, spinel oxide, YbFe ₂ oxide having a O ₄ structure, gallium oxide, titanium oxide, any of niobium oxide and nickel oxide No method of etching the oxide semiconductor film according to claim 1.

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